ext/unicorn_http/httpdate.c

   1 #include <ruby.h>
   2 #include <time.h>
   3 #include <stdio.h>
   4
   5 static const size_t buf_capa = sizeof("Thu, 01 Jan 1970 00:00:00 GMT");
   6 static VALUE buf;
   7 static char *buf_ptr;
   8 static const char week[] = "Sun\0Mon\0Tue\0Wed\0Thu\0Fri\0Sat";
   9 static const char months[] = "Jan\0Feb\0Mar\0Apr\0May\0Jun\0"
  10                              "Jul\0Aug\0Sep\0Oct\0Nov\0Dec";
  11
  12 /* for people on wonky systems only */
  13 #ifndef HAVE_GMTIME_R
  14 static struct tm * my_gmtime_r(time_t *now, struct tm *tm)
  15 {
  16         struct tm *global = gmtime(now);
  17         if (global)
  18                 *tm = *global;
  19         return tm;
  20 }
  21 #  define gmtime_r my_gmtime_r
  22 #endif
  23
  24
  25 /*
  26  * Returns a string which represents the time as rfc1123-date of HTTP-date
  27  * defined by RFC 2616:
  28  *
  29  *   day-of-week, DD month-name CCYY hh:mm:ss GMT
  30  *
  31  * Note that the result is always GMT.
  32  *
  33  * This method is identical to Time#httpdate in the Ruby standard library,
  34  * except it is implemented in C for performance.  We always saw
  35  * Time#httpdate at or near the top of the profiler output so we
  36  * decided to rewrite this in C.
  37  *
  38  * Caveats: it relies on a Ruby implementation with the global VM lock,
  39  * a thread-safe version will be provided when a Unix-only, GVL-free Ruby
  40  * implementation becomes viable.
  41  */
  42 static VALUE httpdate(VALUE self)
  43 {
  44         static time_t last;
  45         time_t now = time(NULL); /* not a syscall on modern 64-bit systems */
  46         struct tm tm;
  47
  48         if (last == now)
  49                 return buf;
  50         last = now;
  51         gmtime_r(&now, &tm);
  52
  53         /* we can make this thread-safe later if our Ruby loses the GVL */
  54         snprintf(buf_ptr, buf_capa,
  55                  "%s, %02d %s %4d %02d:%02d:%02d GMT",
  56                  week + (tm.tm_wday * 4),
  57                  tm.tm_mday,
  58                  months + (tm.tm_mon * 4),
  59                  tm.tm_year + 1900,
  60                  tm.tm_hour,
  61                  tm.tm_min,
  62                  tm.tm_sec);
  63
  64         return buf;
  65 }
  66
  67 void init_unicorn_httpdate(void)
  68 {
  69         VALUE mod = rb_const_get(rb_cObject, rb_intern("Unicorn"));
  70         mod = rb_define_module_under(mod, "HttpResponse");
  71
  72         buf = rb_str_new(0, buf_capa - 1);
  73         rb_global_variable(&buf);
  74         buf_ptr = RSTRING_PTR(buf);
  75         httpdate(Qnil);
  76
  77         rb_define_method(mod, "httpdate", httpdate, 0);
  78 }